There is a device for plasma processing comprising an inductively coupled plasma source that is located inside the processing chamber, consisting of an antenna placed in a dielectric spacer, while the antenna and spacer are placed in a sealed insulating housing. (U.S. Pat. No. 5,580,385, MΠκ (C23C16/00, C23C16/50, published Mar. 12, 1996)
A disadvantage of the known device is unstable operation and low efficiency caused by the fact that alternating magnetic field penetrates through the housing on side of plasma generator or behind it that can lead to unstable spurious discharge.
There is a high-frequency gas discharge ion source of high-density with low-impedance antenna comprising a coil housed in working chamber, formed into a conductive coil, while the gap between the windings is filled with dielectric, and coil itself is separated from the working chamber by dielectric layer, the thickness d of dielectric, separating the coil from the working chamber, does not exceed the value of S, and the distance l from the coil to the nearest conductive surface of the working chamber exceeds triple value of B, where S is the maximum of the values (^,R); R is maximum transverse linear dimension of the conductor, from which antenna spiral is made of; B=^+d, ^=c/ωPe− the depth of penetration of high-frequency electric field in plasma during operation; c−speed of light; ωPe=(4πnee2/m)1/2−electron Langmuir frequency of plasma (c−1); ne−electron density in plasma (cm−3); e, m−charge (4,8×10−10 StatC) and mass of electron (g). (RF Patent number 2171555, H01J37/32; H05H1/46, published Jul. 27, 2001)
The known technology has the following disadvantages: limited scope of application due to the limitation of minimum possible size of working chamber. For example, if the working chamber is a cylinder and the coil is located on its axis, the desired plasma concentration generated is 1012 cm−3, minimum diameter of working chamber is 180 mm larger than the diameter of the coil, low efficiency of application of high frequency current energy to generate plasma in that part of the working chamber where it is required. This is due to the fact that high-frequency fields penetrate into the volume of the working chamber not only where it is required to generate plasma used in the process, but also where they cause spurious discharge obstructing maintaining steady operation of device and causing undesired plasma on those surfaces where it is not required, low reliability as high-frequency fields fill a larger volume than is required, the known device has a large leakage inductance, which leads to excessively high voltage on the coil, which in turn may lead to etching of dielectric.
The closest as for technical nature of the present invention is plasma source, consisting of a helical coil which is placed inside a cylindrical conductive screen, which is opened at one of the bases, with a space between coil windings and between the coil and the screen filled with a dielectric. (U.S. Pat. No. 5,231,334, MΠκ H01J37/08; H01J37/32; H05H1/46, published Jul. 27, 2012)
A disadvantage of the known device is the low efficiency and low operating reliability due to the fact that the screen is located closer to the coil than plasma that leads to an increase in current flowing through the coil and a strong increase in ohmic losses in the screen. Also, due to the strong inductive coupling between the coil and the screen when you turn on the device high power is required to ensure the value of high voltage on coil sufficient for the breakdown of gaseous medium in working chamber.
The technical problems to be solved by the proposed invention are: increasing the efficiency of the device; reducing the level of RF noise; increasing the life of the device; improving the reliability of the device; increasing density of plasma generated; increasing purity of plasma medium; and reducing the size of the device.